By Valerie Volcovici

WASHINGTON, Jan 8 (Reuters) - The United States' decision to withdraw from the United Nations' key climate treaty is a "colossal own goal" that will harm the U.S. economy, jobs and living standards, United Nations climate chief Simon Stiell said on Thursday.

"While all other nations are stepping forward together, this latest step back from global leadership, climate cooperation and science can only harm the U.S. economy, jobs and living standards, as wildfires, floods, mega-storms and droughts get rapidly worse," Stiell said in a statement.   

"It is a colossal own goal which will leave the U.S. less secure and less prosperous."

U.S. President Donald Trump, a vocal critic of renewable energy who has called Climate Change a "con job" and a hoax, went beyond his previous action of withdrawing the U.S. - world's biggest historical greenhouse gas emitter - from the Paris climate agreement by removing the country from the underlying U.N. Framework Convention on Climate Change.

The UNFCCC requires wealthy industrialized countries to take measures to cut their emissions, adopt policies to limit greenhouse gas emissions, publicly report their emissions, and provide funding to help poorer nations address climate change.

On Thursday, U.S. Treasury Secretary Scott Bessent announced the U.S. would immediately withdraw from the UNFCCC's main climate finance mechanism called the Green Climate Fund, and its governing board.

The US also withdrew from the key UN scientific body on climate change called the Intergovernmental Panel on Climate Change. U.S. scientists played a key role in the IPCC's assessments.  

The move drew criticism from European officials as well as environmental groups.

 "The White House doesn’t care about environment, health or (suffering) of people. Peace, justice, cooperation or prosperity are not among its priorities. Not even the great legacy of US to global governance," European Commission Executive Vice President Teresa Ribera, who is responsible for the EU's overall efforts on climate change and the environment, said in a post on Bluesky.

Former U.S. Vice President Al Gore said the U.S. exit from the IPCC, which won a Nobel Peace Prize in 2007, aims to sow doubt around climate science globally even as the rest of the world sticks by the UN climate treaty.

"By withdrawing from the IPCC, UNFCCC, and the other vital international partnerships, the Trump Administration is undoing decades of hard-won diplomacy, attempting to undermine climate science, and sowing distrust around the world," he said.

(Reporting by William James, Valerie Volcovici and Kate Abnett; Editing by Andrew Heavens and Franklin Paul)